INTRODUCTION TO THE THYER TREE VALUATION METHOD 2015
The valuations given by this method are an expression of the positive qualities of the tree, the contribution the tree makes to the landscape and the environment, and the extent to which this is appreciated by the human community.
The Thyer Tree Valuation Method was developed in Sydney, Australia during 1984. It was distributed for public use in 1985 and there have been minor modifications since.
The method was designed to calculate the monetary value of individual trees growing on public or community owned land in city, town and suburban locations. The weighting of the method is set to provide most accurate results for well-separated trees growing in the mid-ring suburbs of the Capital cities, and in regional and country towns. Trees in the CBD of major cities, and in densely populated suburbs would have a higher value than calculated by this method.
The method recognises local knowledge and history of trees but does not address increase of value associated with formal Heritage listing. For trees on LGA, State and National Heritage registers, the value of ‘Penalty Points’ prescribed in legislation for damage to the listed tree, should also be considered.
The method is not intended for use within bushland areas, or on rural land. However, it may be used in those locations to provide a starting figure which can then be adjusted to reach an agreed valuation.
The method is not recommended to calculate the value to the owner, of trees growing on privately owned land. Values calculated for trees on private land include the value of those trees to the community, and no division of those separate values is provided in the method. A separate valuation method was developed in 2012 and is available to calculate the value to the owner, of private trees in all city, suburban, town, rural and bushland locations.
The State or Community owner of a tree, and nearby residents may calculate different values depending on their opinion of, or problems with a tree. Damage caused by the tree, cost to repair that damage, and cost to repair or remove the tree are not included in the method and must be costed separately.
The method is summarised and presented as a one-page worksheet and spreadsheet. People using this method to value trees should be qualified, experienced and knowledgeable in arboriculture and landscape assessment, and trained in the use of this method.
The method combines four factors to establish a Significance Index for each tree:
- Size measures of Height, Crown side view area, Dripline diameter, and Girth.
- Age of the tree.
- Physical assessment of the tree and location.
- Social benefit and how the tree is appreciated.
The method has been designed to give a Significance Index of approximately 1.0 to an average nursery production tree in a 5 litre/200mm pot, planted in a recently completed landscape. A very large, old, socially significant tree may have a Significance Index of 12,000 or more.
To calculate $value, the Significance Index is multiplied by the Planting Cost which is the local landscape industry current average 'supply and install' cost of a tree growing in a 5 litre/200mm pot. This cost is used because it is the real cost currently paid for trees planted in the landscape, is made up of plant production costs, labour costs and current technology costs, and reflects the willingness of members of the community to pay for those trees.
To avoid establishing the local Planting Cost for every valuation, the recommended Planting Cost for use is that published by the various State Landscaper Associations in their Schedule of Rates. The appropriate rate is a “charge-out” rate which includes all the costs, overheads and profit of a professional landscaper installing trees that meet AS 2303:2018, Tree Stock for Landscape Use, as part of a landscaping project. The rate should be a general rate for the most commonly planted tree species, and for all projects not a rate which is for only residential or commercial projects.
The recent Schedule of Rates of some Landscape Associations do not include the rate as described above. For that reason, the following historic rates which do meet the above conditions, are recommended as a base Planting Cost, to be updated to present value by use of a Consumer Price Index (CPI) calculation:
LANDSCAPE NSW & ACT Guideline Schedule of Rates for Landscape Works Ed 14
(Dec 2010) = $24.20
LANDSCAPING Victoria RATES VOLUME 6 a guide for landscaping works
(June 2015) = $30.00
The following CPI calculator on the Reserve Bank of Australia website is recommended:
The historic Planting Cost should be updated to the Financial Quarter of the date of valuation using that CPI calculator.